JP2504845B2 - Solid-state imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a solid-state image pickup device capable of obtaining an image signal of both an erect image and a mirror image.

<Prior Art> In order to obtain a mirror image signal from a two-dimensional solid-state image pickup device by purely electronic processing, a video signal is used in a line memory different from that of the image pickup device.
Reverse the time in the line.

The solid-state image sensor is read with the horizontal scanning direction reversed.

There are two known methods. Among these methods, the circuit scale around the image sensor becomes large, and additional problems such as S / N deterioration are likely to occur and cannot be said to be excellent methods.

This method will be described by taking a CCD imager, which is the mainstream of solid-state image pickup devices, as an example. In the following discussion, the case of the interline transfer type CCD is taken as an example, but the case of the frame transfer type CCD can be discussed in exactly the same way. FIG. 4 shows an example in which the above method is applied to an interline transfer CCD. Of the photoelectric conversion units arranged in a matrix, the i-th row and the j-th column are aij, and the signals from the photoelectric conversion units are vertically transferred by the clocks of φ _V1 , φ _V2 , φ _V3 , and φ _V4. Vertical CCD unit, and signals from the vertical CCD unit are transferred in the horizontal direction by the clocks of φ _H1 , φ _H1 ′, φ _H2 , and φ _H2 ′. Horizontal CCD that is transferred in the horizontal direction.
Section, a first signal charge detection unit A1 provided at the left end of the horizontal CCD, and a second signal charge detection unit A2 provided at the right end of the horizontal CCD. Where horizontal clock φ
_By setting the timing of _H1 , φ _H1 ′, φ _H2 , and φ _H2 ′ to the first mode, the horizontal CCD transfer direction is set to the left side, and the first
The output signal OS of the erect image is obtained from the signal charge detection unit A1 of
Also, by setting the horizontal clock timing to the second mode in which the phase is inverted from the first mode, the horizontal CCD
Is set to the right, and a mirror image output signal OS 'is obtained from the second signal charge detection unit A2.

<Problems to be Solved by the Invention> However, the above-mentioned configuration has the following problems.

(A) The characteristics of the signal charge detectors A1 and A2 do not match, and the image quality does not match between the erect image and the mirror image.

(B) Since the output terminal is divided into two parts, the configuration of the external signal processing system becomes complicated.

(C) The number of element terminals increases as the number of output circuits increases.
In addition, an extra-element power supply switching circuit or the like is required to suppress unnecessary power consumption.

In view of the above problems, the present invention provides a solid-state imaging device that can obtain an erect image signal and a mirror image signal from the same output terminal by simply changing the drive pulse timing without increasing the number of output circuits. It is a thing.

<Means for Solving Problems> In order to solve the above problems, the present invention includes a vertical transfer unit that transfers the signal charges detected by the photoelectric conversion unit, and a signal coupled to the vertical transfer unit. In a solid-state imaging device including a horizontal transfer unit for deriving charges, a normal horizontal CCD having a signal charge detection unit only at one end is used as a first horizontal transfer unit, and the signal of the first horizontal transfer unit is used. It is extended from the side opposite to the charge detection section and is turned by 180 ° to the side opposite to the vertical transfer section, and then is extended in parallel with the first horizontal transfer section and immediately before the signal charge detection section. A second horizontal transfer portion is formed so as to join the portion, and the arrangement direction of the electrodes is changed in the first horizontal transfer portion.

<Operation> With this configuration, when the drive waveform applied from the outside is in the first mode, the charge transfer direction is the second horizontal transfer portion → first
When the driving waveform applied from the outside is in the second mode, the charge transfer direction is the first horizontal transfer section → the second horizontal transfer section → the signal charge detection section. In this order, the horizontal scanning directions are opposite to each other in the first mode and the second mode, and by switching between the two modes, two types of erect image / mirror image video signals can be obtained from the same output terminal.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 1A is a plane pattern configuration diagram of a main part of the solid-state imaging device according to the present embodiment. The figure shows a horizontal transfer section, which is not shown in the figure, but like the conventional solid-state imaging device, the photoelectric conversion sections arranged in a matrix detect incident light and detect the detected signal. Vertical transfer sections V _{1 to} V _n for transferring charges in the vertical direction are connected, and the signal charges transferred from the vertical transfer sections are given to the horizontal transfer section shown in the figure.

The alternate long and short dash line area is the active area forming the CCD transfer channel, and the area outside this is the channel stop area. The solid line indicates the transfer electrode group, and as shown in the sectional structure of FIG. 1 (b), the transfer of the signal charge is directed to the surface of the N ⁻ semiconductor layer under the electrode P.
An upper electrode (a narrow electrode in the drawing) into which a type impurity is ion-implanted and a lower electrode (a wide electrode in the drawing) formed by overlapping the upper electrode with an end portion are arranged so as to cover a two-dimensional plane. . (In the figure, the electrodes are separated from each other for easy understanding.) Two pairs of upper and lower electrode pairs form one bit, and one electrode of the lower electrode in one bit is connected to the vertical transfer portion. The signal charge is transferred.

The transfer electrode group includes a horizontal transfer electrode group S into which a signal charge from the vertical transfer section is introduced, a signal charge detection electrode group G for deriving a signal from the horizontal transfer electrode group to an output section, and the horizontal transfer electrode. The contact transfer electrode group M for transferring and deriving in one of the directions I and II opposite to each other while utilizing the group S.
The horizontal transfer parts L ₁ and L _{2 of the} book are combined. As the electrodes formed on the surface of the semiconductor substrate, the above two horizontal transfer parts are used.
Introducing the transfer clock signals φ _A and φ _B to the corresponding electrodes in the two horizontal transfer sections is switched so that it is created in common for L ₁ and L ₂ and reverse transfer I and II are possible. .

Each transfer electrode group G, S, M Metal wiring part shown by the dotted line through the contact opening shown by
Clock signals φ ₁ , φ ₂ , φ _A , and φ _B are applied from W ₁ , W ₂ , W _A , and W _B. A junction diode D for detecting a charge, which is indicated by hatching, is formed on the electrode at the end of the signal charge detection electrode group G to which the DC potential OG is applied, and a switching transistor is formed.
The reset clock φ _R input to the Tr resets the reset potential RD for each pixel signal, and the diode D
The potential change of is output as the output signal OS by the buffer amplifier A ₀ . Of the horizontal transfer electrode group and the communication transfer electrode group, the electrodes to which clocks φ _A and φ _B are applied and the signal charge detection electrodes G1 and G
A potential barrier is formed below 2 to direct the transfer. n vertical CCD transfer channels are V ₁ , ..., V _n
, And these are connected to one of the horizontal transfer electrodes of each bit to input a signal. In the solid-state imaging device having the horizontal transfer section in which the transfer section is connected to the bent transfer electrode group as described above, the first drive mode is set to φ _A = φ ₁ ,
Consider the case of two-phase driving with φ _B = φ ₂ . The transfer direction at this time is as shown by the solid arrow I, and the charge detection diode D outputs in the order of V ₁ , ..., V _n to obtain an erect image video signal. Next, the second drive mode is changed to φ _A = φ ₂ , φ
_When two-phase driving is performed with _B = φ ₁ , the transfer direction becomes as shown by the broken line arrow II and V _n ,
…, V ₁ are output in that order to obtain a mirror image signal. FIG. 2 is a diagram showing timings in these two driving modes, and FIG. 3 shows potential changes in directions I and II. If the addresses of the photoelectric conversion units arranged in a matrix form the i-th row and the j-th column from the side closer to the output unit, the i-th row signal is 1 when viewed in the i-th horizontal scanning period in the first drive mode. It is sequentially output from the column. That is, an erect image video signal is output in real time. On the other hand, in the second driving mode, when viewed in the i-th horizontal scanning period, the signal of the (i-1) th row is sequentially output in the reverse direction from the n-th column. That is, the mirror image signal is delayed by 1H and then output. It is to be noted that matching the timing at which the leading n-th column signal is output in the second drive mode with the timing at which the leading first-column signal is output in the first drive mode is a clock signal within one horizontal scanning period. This can be easily performed by adjusting the transfer period from the horizontal transfer section to the signal charge detection section by.

As shown in Fig. ₂ , the transfer period of φ ₁ and φ ₂ within 1H Then (Fig. 2 shows the case of contact transfer electrode group m = 4), 1H
Immediately after the horizontal column signal is read out, the signals of V _n are accumulated in V ₁ , ..., S _n in the gate region S ₁ in the normal mode, and V _n , ..., R _n in the gate region R ₁ in the mirror image inversion mode. The V ₁ signal is accumulated. Therefore, the timings at which the signals V ₁ , ..., V _n are output to the output terminals are the same in the normal mode and the mirror image inversion mode. (However, it is delayed by 1H in the mirror image inversion mode.) There is a 1H time difference between the first mode for obtaining an erect image and the second mode for obtaining a mirror image, but an image for one scanning line on the actual screen. It is a vertical movement of, and there is no problem at all.

<Effects of the Invention> As described above, according to the present invention, by switching the external drive timing of the solid-state imaging device between two modes,
It is possible to select and obtain either an erect image or a mirror image signal from the same output terminal, and its functional effect is great. Further, despite the large added value, the number of terminals of the image pickup device and the power consumption are hardly increased.

[Brief description of drawings]

FIG. 1 (a) is a configuration diagram showing a main part of a solid-state imaging device according to an embodiment of the present invention, FIG. 1 (b) is a cross-sectional view of a substrate of the same embodiment, and FIG. 2 is a solid-state imaging device of FIG. 3 is a drive timing diagram of the apparatus, FIGS. 3 (a) and 3 (b) are model diagrams of the operating state of the same embodiment, and FIG. 4 is a configuration diagram of a conventional solid-state imaging device for obtaining an erect image / mirror image. S: Horizontal transfer electrode group, G: Signal charge detection electrode group, M
...... Communication transfer electrode group, φ ₁ , φ ₂ , φ _A , φ _B …… Clock signal, V _{1 to} V _n …… Vertical transfer unit

Claims (1)

(57) [Claims] 1. A solid-state imaging device in which a signal charge detected by a photoelectric conversion unit is output from a signal detection unit coupled to a horizontal transfer unit via a vertical transfer unit, wherein the horizontal transfer unit includes a first horizontal transfer unit and a first horizontal transfer unit. Two horizontal transfer sections, one end of each of the first horizontal transfer section and the second horizontal transfer section is connected to a common signal charge detection section, and the other ends are connected to both horizontal transfer sections in a bent shape. When the arrangement directions of the electrodes in the first horizontal transfer unit and the second horizontal transfer unit are rearranged and the driving waveform applied from the outside is in the first mode, the signal charges are applied from the outside in the first direction. A solid-state imaging device, wherein when the waveform is in the second mode, the signal charges are transferred in a second direction opposite to the first direction, and two types of image signals of an erect image and a mirror image are obtained.